Light emitting device

ABSTRACT

A light emitting device includes a molded package and one or more light emitting components. The molded package includes a recess, two leads, and a molded resin part. A part of the recess is defined by a side wall formed from the molded resin part. At least one of the two leads includes an upper-surface portion exposed from a bottom surface of the recess. The at least one of the two leads includes a groove at an upper surface thereof. The groove is filled with a part of the molded resin part. The part of the molded resin part includes a first portion and a second portion. The first portion is exposed from the bottom surface of the recess. The second portion connects with a bottom surface of the side wall.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of the U.S. patentapplication Ser. No. 13/744,586, filed Jan. 18, 2013, which claimspriority under 35 U.S.C. § 119 to Japanese Patent Application No.2012-010449, filed Jan. 20, 2012. The contents of these applications areincorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a light emitting device.

Description of the Related Art

A frame insert type resin package for a light emitting device havingsuch a configuration that a lead is exposed from a rear surface of amolded resin to enable an effective heat discharge from a light emittingcomponent mounted on a recess portion of the package to a mountedsubstrate via the lead (see, JP 2008-251937 A) is known. Such a packagethat formation of an anchor groove on the lead and the subsequentfilling of the molded resin into the anchor groove cause a adhesion areabetween the lead and the molded resin to increase is also known (see,for example, JP 2011-146524 A).

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a light emittingdevice includes a molded package and one or more light emittingcomponents. The molded package includes a recess, two leads, and amolded resin part. A part of the recess is defined by a side wall formedfrom the molded resin part. At least one of the two leads includes anupper-surface portion exposed from a bottom surface of the recess. Theat least one of the two leads includes a groove at an upper surfacethereof. The groove is filled with a part of the molded resin part. Thepart of the molded resin part includes a first portion and a secondportion. The first portion is exposed from the bottom surface of therecess. The second portion connects with a bottom surface of the sidewall.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings.

FIG. 1A is a perspective view of a top surface of the light emittingdevice according to the present embodiment and FIG. 1B is a perspectiveview of a rear surface thereof.

FIG. 2 is a top surface view when a sealing resin of the light emittingdevice according to the present embodiment is removed.

FIG. 3 is a cross sectional view of the light emitting device of FIG. 2taken along line 2A-2A.

FIG. 4 is a cross sectional view illustrating a molding process of themolded package according to the present embodiment.

FIG. 5 is a cross sectional view for illustrating the molding process ofthe molded package according to the present embodiment.

FIG. 6 is a top view of the molded package according to the presentembodiment.

FIG. 7 is a cross sectional view of the molded package of FIG. 6 takenalong line 6A-6A.

FIG. 8 is a cross sectional view of the molded package of FIG. 6 takenalong line 6B-6B.

FIG. 9 is a top view illustrating a lead frame to which leads aresecured according to the present embodiment.

FIG. 10 is a rear surface of the lead frame to which leads are securedaccording to the present embodiment.

FIGS. 11A to 11C are partial cross sectional views of the leadsaccording to the present embodiment.

FIGS. 12A to 12C are partial cross sectional views of the leadsaccording to the present embodiment.

FIG. 13A is a perspective view of a front surface of a modification ofthe light emitting device according to the present embodiment and FIG.13B is a perspective view of a rear surface of the same.

FIG. 14A is a line drawing of a photograph of a front surface of acomparative molded package and FIG. 14B is a line drawing of aphotograph of a front surface of the molded package according to thepresent embodiment.

FIG. 15 is a line drawing of a photograph of a cross section of themolded package according to the present embodiment.

FIG. 16 is a cross sectional view for illustrating molding process ofthe molded package according to a comparative example.

FIG. 17 is a top view of the molded package according to the comparativeexample.

FIG. 18 is cross sectional view of the molded package according to thecomparative example.

FIG. 19 is a cross sectional view illustrating a state of the moldedpackage according to the comparative example before being subjected tothe molding process.

DESCRIPTION OF THE EMBODIMENTS

The embodiments will now be described with reference to the accompanyingdrawings, wherein like reference numerals designate corresponding oridentical elements throughout the various drawings.

In the present embodiment, technical terms such as “inside”, “outside”,“upper edge”, and “below” indicate a position and a direction withreference to a center of the bottom surface of the recess portion.

In the present embodiment, the “inside upper edge” of the groove is anedge portion near the center of the bottom surface of the recess portionof the molded resin among two edge portions (i.e., upper edges) opposingto each other in a width direction in an opening of the groove and the“outside upper edge” indicates an edge portion away from the center ofthe bottom surface of the recess portion of the molded resin.

The “groove” of the present embodiment indicates a groove which isformed into a recess shape and is configured such that, in the openingin the surface of the lead, a side wall of the recess portion of themolded resin opposes to an inside upper edge. Preferably, the opening ofthe groove has almost a constant width throughout the groove. However, adistance between the side wall of the recess portion of the molded resinand the inside upper edge and a width of the opening may be configuredto be partially larger or smaller.

As illustrated in FIGS. 1 to 3, a light emitting device 50 according tothe present embodiment includes a molded package 10, a light emittingcomponent 40, and a sealing resin 52.

In the present embodiment, the “light emitting component 40” indicates acomponent involving a light emitting element and includes the lightemitting element (e.g., a LED) itself and a component composed of thelight emitting element and a submount. In the present embodiment, thelight emitting component 40 consists of a light emitting element.

The sealing resin 52 seals a recess portion 12 of a molded resin 11after accommodating the light emitting component 40 in the recessportion 12 in order to protect the light emitting component 40 from theexternal environment.

A molded package 10 according to the present embodiment includes amolded resin 11 and at least one lead (i.e., two leads 20 and 30 in thepresent embodiment).

The molded resin 11 has a recess portion 12 on a top surface thereof inorder to accommodate the light emitting component 40 in the recessportion 12. The recess portion 12 is enclosed by side wall 13.

The leads 20 and 30 are partially exposed from a bottom surface 121 ofthe recess portion 12 of the molded resin 11 and extend downward theside wall 13 of the recess portion 12 of the molded resin 11 (see, FIGS.2 and 3). The two leads 20 and 30 are spaced to each other and a sectiontherebetween is filled with the molded resin 11.

In the light emitting device 50 of the present embodiment, an exposedsurface 21 a of one of the leads (i.e., the first lead) 20 is providedwith one or more (i.e., two in FIG. 2) light emitting component 40 (41and 42). The second lead 30 is used as an area for wire bonding and isprovided with a zener diode 43 disposed thereon. The second lead 30 hasa recess portion between the area for the wire bonding and the areaprovided with the zener diode disposed thereon, thereby improving theadhesion area between the second lead 30 and the sealing resin. Therecess portion of the second lead is formed so as to be connected to abelow described groove 24X to be filled with the molded resin 11,thereby preventing a joint member of the zener diode from eroding thearea for wire bonding.

The light emitting component 40, the first lead 20, and the second lead30 are electrically connected to each other via a bonding wire BW. Asillustrated in FIG. 2, when the light emitting device includes two lightemitting components 41 and 42, the wire bonding may be configured suchthat the first light emitting component 41 is connected to the firstlead 20 via the bonding wire BW, the second light emitting component 42is connected to the second lead 30 via the bonding wire BW, and furtherfirst light emitting component 41 is connected to the second lightemitting component 42 via the bonding wire BW (i.e., the series wiring).Alternatively, each of the two light emitting components 41 and 42 maybe connected to the first lead 20 and the second lead 30, respectively,via the bonding wire BW (i.e., the parallel wiring).

As illustrated in FIG. 2, the first lead 20 and the second lead 30 hasgrooves 24 formed on surfaces 21, and 31 of the leads along at leastportions of the side wall 13 (i.e., a peripheral area). Each groove 24has an inside upper edge 241 and an outside upper edge 242.

In the present embodiment, the “at least a portion of the side wall”indicates “a portion of a periphery” of inner surfaces of the side wall13 disposed peripherally (i.e., formed into a closed ring shape) whenviewed from a top thereof, as shown in FIG. 6.

In the preset embodiment, the inside upper edge 241 of each groove 24 isexposed from the bottom surface 121 of the recess portion 12 of themolded resin 11 and the outside upper edge 242 of each groove 24 isembedded within the molded resin 11. For example, as illustrated in FIG.3, skirt portions of the side wall 13 of the recess portion 12 (i.e., aportion of the molded resin 11) are embedded within the groove 24 toform a portion of a bottom surface 121 of the recess portion 12. Aportion of the molded resin 11 (i.e., a portion of the groove filledwith the resin 11 a) is substantially filled in the groove 24 in itsentirety.

In the present embodiment, the inside upper edge 241 of each groove 24is exposed from the bottom surface 121 of the recess portion 12 of themolded resin 11 and the outside upper edge 242 of each groove 24 isembedded within the molded resin 11, so that the portion of the groovefilled with the resin 11 a within the groove 24 is connected to the body11 b of the molded resin 11 at a side of the outside upper edge 242 whenviewed from the cross section (FIG. 3) and the portion of the groovefilled with the resin 11 a appears to be a portion of the bottom surface121 of the recess portion 12 at a side of the inside upper edge 241 whenviewed from the top surface.

As illustrated in FIG. 3, an area of a side of the inside upper edge 241(i.e., an area exposed from the bottom surface 121 of the recess portion12) of a surface 21 a of the first lead 20 and the portion of the groovefilled with the resin 11 a are smoothly continues in the inside upperedge 241, i.e., substantially has no step. The area on the side of theinside upper edge 241 can be configured only with a curved surface butis preferably at least partially formed with a horizontal surface inflush with the exposed surface 21 a of the lead 20 (e.g., adjacentportion of the inside upper edge 241). The area on the side of theinside upper edge 241 of the portion of the groove filled with the resin11 a is pressed by a stress F₁ during the reflow soldering. At the time,if the area on the side of the inside upper edge 241 includes ahorizontal portion, the stress F₁ is oriented vertically (i.e.,vertically downwardly) with respect to the horizontal surface (detaileddescription follows below).

As illustrated in FIGS. 1A and 3, the first lead 20 and the second lead30 are preferably exposed from a rear surface 14 of the molded resin 11.Accordingly, heat generation by the light emitting element 40 can beeffectively discharged to the outside of the recess portion 12 via thefirst lead 20 and the second lead 30. With such a configuration, an edgeportion of a boundary surface 61 (i.e., a boundary 61 a) between thefirst lead 20 and the molded resin 11 and an edge portion of a boundarysurface 62 (i.e., a boundary 62 a) between the second lead 30 and themolded resin 11 are exposed from the rear surface 14 of the molded resin11. The boundary surfaces 61 and 62 extends through an area between thebottom surface 243 of the groove 24 and the portion of the groove filledwith the resin lie so as to be successive into the recess portion 12 ofthe molded package 10.

With a molded package 100 (see, FIGS. 16 to 18) according to thecomparative example, if the light emitting device having a configurationillustrated in FIG. 3 is manufactured, the soldering flux moltenaccording to the reflow soldering may extend from a boundary 610 a of arear surface 140 of the molded package 100 to reach a recess portion 120through a boundary surface 610 when the light emitting device is mountedon the mounted substrate.

On the other hand, in the light emitting device 50 according to thepresent embodiment, the sealing resin 52 filled into the recess portion12 of the molded package 10 expands by heat during the reflow solderingto generate a stress F₁ that presses the area on the side of the insideupper edge 241 of the portion of the groove filled with the resin 11 a(i.e., the area exposed from the bottom surface 121 of the recessportion 12) downwardly (i.e., toward the bottom surface 243 of thegroove 24). Further, the molded resin 11 also expands so that theportion of the groove filled with the resin 11 a presses side surfacesand the bottom surface 243 within the groove 24. In other words, due tothe synergistic effect between the thermal expansion of the sealingresin 52 and the thermal expansion of the portion of the groove filledwith the resin 11 a, the stress that the portion of the groove filledwith the resin 11 a presses downwardly (i.e., toward the bottom surface243 of the groove 24) increases. Accordingly, especially, inbetween theportion of the groove filled with the resin 11 a and the bottom surface243 of the groove 24 of the boundary surface 61, the adhesion becomesstronger and thus high restraint exercises against the invasion of thesoldering flux. As a result thereof, a disadvantage that the solderingflux reaches the recess portion 12 can be decreased in comparison with acase of the light emitting device using the molded package 100.

A direction of the stress F₁ is vertical with respect to a surface ofthe portion of the groove filled with the resin 11 a. Consequently, asillustrated in FIG. 3, if at least the area adjacent to the inside upperedge 241 of the surface of the portion of the groove filled with theresin 11 a is formed into a horizontal surface in flush with the exposedsurface 21 a of the lead 20, the stress F₁ applied to the horizontalsurface is oriented in a vertical downward direction. As a resultthereof, a contact surface between the portion of the groove filled withthe resin 11 a and the bottom surface 243 of the groove 24 can bepreferably effectively tightly adhered to each other.

When the surface of the portion of the groove filled with the resin 11 ais formed into a curved surface, the stress F₁ applied to the curvedsurface in a direction perpendicular to a tangential line direction ofthe curved surface is oriented obliquely with respect to a contactsurface between the portion of the groove filled with the resin 11 a andthe bottom surface 243 of the groove 24. As a result thereof, an effectof adhesion of the contact surface can be produced owing to a componentin a vertical downward direction of the stress F₁.

Since the stress F₁ for pressing the portion of the groove filled withthe resin 11 a downwardly is generated during the reflow soldering, themolded resin 11 can be effectively prevented from being separated fromthe first lead 20 and the second lead 30. More specifically, the sidewall 13 of the molded resin 11 are applied with the outwardly actingstress F₂ due to the thermal expansion of the sealing resin 52 duringthe reflow soldering. The stress F₂ can act so as to separate the moldedresin 11 from the first lead 20 and the second lead 30.

However, in the present embodiment, the generation of the stress F₁ thatpresses the portion of the groove filled with the resin 11 a downwardlyallows tight bonding of the molded resin 11 with respect to the firstlead 20 and the second lead 30. In comparison with the anchor groovewhich is completely embedded into the molded package as discussed in JP2011-146524 A, an effect to prevent the molded resin 11 from beingseparated from the first lead 20 and the second lead 30 can be enhancedby providing the groove 24 exposed at the inside upper edge 241according to the present embodiment.

In the light emitting device 50 according to the present embodiment,since an area of the joining portion between the sealing resin 52 andthe molded resin 11 increases according to the portion of the groovefilled with the resin 11 a within the groove 24, a joining force betweenthe sealing resin 52 and the molded package 10 can be made stronger.

The sealing resin 52 is fixed to the molded package 10 such that thesealing resin 52 is bonded to the molded resin 11, the first lead 20,and the second lead 30 exposed in the recess portion 12. The sealingresin 52 is more strongly bonded to the molded resin 11 than the leads20 and 30. Therefore, as an area at which the sealing resin 52 and themolded resin 11 are joined increases, a bonding force between thesealing resin 52 and the molded package 10 becomes stronger.

A direction of the joining area between the sealing resin 52 and themolded resin 11 (i.e., a direction orthogonal to a tangential linedirection of the area) is different from each other between a portionbetween the side wall 13 and the sealing resin 52 and a portion betweenthe portion of the groove filled with the resin 11 a and the sealingresin 52 in the joining area. Therefore, a resistance force against thestress applied to the sealing resin 52 also differs. As a resultthereof, when a stress is applied in a direction in which the sealingresin 52 is separated from the molded package 10, a resistance forceagainst the stresses from all the directions improves because theresistance force generated between the side wall 13 and the sealingresin 52 and the resistance force generated between the portion of thegroove filled with the resin 11 a and the sealing resin 52 complement toeach other.

Therefore, manufacturing of the light emitting device 50 by using themolded package 10 according to the present embodiment enables to preventthe sealing resin 52 from being separated from the molded package 10.

As illustrated in FIG. 16, a molded resin 110 of a molded package 100according to the comparative example is manufactured according tomolding by using a metal mold 90 consisting of an upper metal mold 91and a lower metal mold 92. More specifically, a space of the metal mold90 is filled with molten resin while the leads 200 and 300 are heldbetween the upper metal mold 91 and the lower metal mold 92. The uppermetal mold 91 has a convex portion 93 corresponding to a recess portion120 of the molded resin 110. It is desirable that no invasion of themolten resin occurs into an area (i.e., the metal mold-lead contactarea) where a surface of the convex portion 93 and surfaces of the leads200 and 300 directly contact to each other. However, chamfering (i.e., Rchamfering or C chamfering) is provided to corners 93 c of the convexportion 93 of the upper metal mold 91, thereby attempting to improvereleasability of the upper metal mold 91. If the metal mold 90 is usedfor molding, burr of the molded resin 110 is formed on surfaces of theleads 200 and 300 exposing to the recess portion 120 of the molded resin110 (see, FIGS. 17 and 18). The burr may be formed for the reasons asdescribed below.

As illustrated in FIG. 19, when the corner 93 c of the convex portion 93of the upper metal mold 91 is subjected to chamfering processing, aclearance CL having a sharp angle is created between the corner 93 c andeach of the leads 200 and 300. Upon injection of the molten resin intothe metal mold 90, a stress is applied concentrically to a top of theclearance CL from the molten resin and, therefore, the molten resinoozes out into a metal mold-lead contact area from a top of theclearance CL. The molten resin oozing out from the top of the clearanceCL becomes a burr 80 after curing the molten resin.

Spreading of the burr 80 over the leads 200 and 300 invites a poorbonding upon die bonding between the first lead 200 and the lightemitting component and a poor bonding upon wire bonding between thesecond lead 300 and the light emitting component. Since the burr 80 isformed into an irregular shape, the burr 80 causes disfigurement of therecess portion 120 of the molded package 100 when viewing from a topthereof (see, FIG. 17).

In the light emitting device 50 according to the present embodiment,however, the burr is less generated on the bottom surface 121 of therecess portion 12 of the molded package 10. The reasons thereof follow.

The molded resin 11 of the molded package 10 is molded by using themetal mold 90 consisting of the upper metal mold 91 and the lower metalmold 92 (see, FIGS. 4 and 5). The upper metal mold 91 has a convexportion 93 corresponding to the recess portion 12 of the molded resin11. Corners 93 c of the convex portion 93 are subjected to thechamfering processing (i.e., R-chamfering processing or C-chamferingprocessing).

As illustrated in FIG. 4, the upper metal mold 91 and the lower metalmold 92 cooperatively hold the first lead 20 as well as cooperativelyhold the second lead 30 during the molding of the molded resin 11. Atthe time, as illustrated in FIG. 5, since the groove 24 is positionedimmediately below the corner 93 c of the convex portion 93 of the uppermetal mold 91, no clearance CL having a sharp angle (see, FIG. 19) isformed between the corner 93 c and the leads 20 and 30. In other words,there is no portion at which the stress tends to be concentrated at thetime of filling the molten resin into the metal mold 90 (e.g., no top ofthe clearance CL having a sharp angle). Therefore, the molten resin doesnot ooze out into the area where the metal mold 90 contacts the firstlead 20 (and the area where the metal mold 90 contacts the second lead30), so that no burr 80 of the molded resin 11 (see, FIGS. 17 and 18) isgenerated on the surfaces of the first lead 20 and the second lead 30.

In the resulting molded package 10, no burr is generated at the boundarybetween the molded resin 11 (11 a) and the surfaces 21 and 31 of theleads 20 and 30, so that the boundary matches the inside upper edge 241of the groove 24 (see, FIGS. 6 though 8).

As described above, in the molded package 10 according to the presentembodiment, the groves 24 provided on the leads 20 and 30 are positionedimmediately under the corners 93 c of the convex portion 93 of the uppermetal mold 91 during the manufacturing of the molded package 10. As aresult thereof, the burr 80 can be effectively prevented from beinggenerated. Therefore, in the light emitting device 50 using the moldedpackage 10 according to the present embodiment, poor bonding due to theburr 80 does not occur and, therefore, the burr 80 shall not spoil theappearance of the light emitting device 50.

In the light emitting device 50 of the present embodiment, the grooves24 are recess portions extending in a belt like shape and have aconstant width of openings in the surfaces 21 and 31 of the leads 20 and30 (i.e., a constant distance between the inside upper edge 241 and theoutside upper edge 242). For example, as illustrated in FIG. 9, thegroove 24 is provided on each of the leads 20 and 30 such that thegroove is formed into a channel shape provided along three sides of eachof the leads 20 and 30 and each corresponding inside upper edge 241 andthe outside upper edge 242 may be connected at an upper end edge 244 ofthe groove 24. Since an opening of each groove 24 is enclosed by theinside upper edge 241, the outside upper edge 242, and the upper endedge 244, when the soldering flux entered from the boundaries 61 a and62 a enters into the groove 24, the soldering flux needs to climb up toan upper edge of the opening of the groove 24 in order to enter thegroove 24. Accordingly, entry of the soldering flux can be bettercontrolled.

The rear surfaces 22 and 32 of the first lead 20 and the second lead 30are exposed from the rear surface 14 of the molded resin 11 and areformed into concave portions on the sides of the front surfaces of theleads from the edges of the rear-surface exposed portion. The concaveportions (i.e., the rear surface concave portions) 221 and 321 arecovered by the molded resin 11 (see, FIG. 10). The peripheral portionsof the rear surfaces 22 and 32 of the first lead 20 and the second lead30 are formed into a canopy shape and, thus, an entry path (i.e.,boundary surfaces 61 and 62) through which the soldering flux enters therecess portion 12 during the reflow soldering becomes longer, so that aneffect to decrease the entry of the soldering flux to the recess portion12 can be produced. The “canopy shape” indicates a shape that, asillustrated in FIG. 10, a side of the surface 21 of the lead 20protrudes more than a side of the rear surface 22 of the lead 20.

When the grooves 24 are formed immediately above the rear surface recessportions 221 and 321, since the thickness of the leads 20 and 30 becomeremarkably thinner, the strength of the leads 20 and 30 decreases. Thus,preferably, the grooves 24 are formed on positions rather interior ofthe positions immediately above the rear surface recess portions 221 and321 (see, FIGS. 7 to 10). However, under the circumstances that thesurface areas of the leads 20 and 30 become narrower according todownsizing of the light emitting device 50, the grooves 24 may be formedimmediately above the rear surface recess portions 221 and 321 partiallyor in its entirety.

In the present embodiment, the “rear surface recess portion” may have aninner surface formed into a curved surface as illustrated in FIGS. 11Ato 11C and FIGS. 12A and 12B. Alternatively, the “rear surface recessportion” may be formed into a step as illustrated in FIG. 12C.

A cross sectional shape of the groove 24 can be formed into variousshapes such as a rectangular shape (see, FIGS. 11A and 12C), atrapezoidal shape (see, FIGS. 11B and 11C), a circular shape (see, FIG.12A), and a polygonal shape (see, FIG. 12B). Preferably, as illustratedin FIGS. 11B and 11C and FIGS. 12A and 12B, the groove 24 has themaximum width 24Wmax larger than a width 24W between the inside upperedge 241 and the outside upper edge 242 in a depth direction D. In thepresent embodiment, the “depth direction D” is a direction oriented tothe rear surfaces 22 and 32 of the first lead 20 from the surfaces 21and 31 of the first lead 20.

In other words, the groove 24 preferably has a cross section of whichmaximum width 24Wmax of the inside of the groove 24 is larger than thewidth 24W of the opening in the surface 21 of the first lead 20. As itis apparent from FIGS. 11A to 11C, in three types of grooves 24 a to 24c having the same width 24W of the opening and the same depth 24D of thegroove 24 to each other, the grooves 24 b and 24 c having the crosssection of which width 24W is narrower than the maximum width 24Wmax hasan inner surface of the groove 24 viewed in cross section longer thanthe groove 24 a having the cross section of which width 24W is equal tothe maximum width 24Wmax. Therefore, when the molded package 10 ismanufactured by using the lead 20, the entry path through which thesoldering flux enters the recess portion 12 (i.e., the boundary surface61 between the first lead 20 and the molded resin 11) during the reflowsoldering becomes longer, resulting in causing the soldering flux tohardly enter the recess portion 12.

When the groove 24 is configured to have a cross section having a width24W narrower than the maximum width 24Wmax, the maximum width(corresponding to the maximum width 24Wmax of the groove 24) of theportion of the groove filled with the resin 11 a filled into the groove24 becomes larger than the width 24W of the groove 24. Therefore, theportion of the groove filled with the resin 11 a shall not come off fromthe groove 24. As a result thereof, the molded resin 11 can beeffectively prevented from being separated from the first lead 20.

As illustrated in FIGS. 12A and 12B, a configuration that the crosssection of each of the grooves 24 d and 24 e becomes narrower from thesurface 21 to the rear surface 22 of the lead 20 after once becomingwider enables to decrease an area necessary for the groove 24 in thesurface of the lead and also decrease the depth of the groove 24, sothat the entry path through which the soldering flux enters the recessportion 12 can be elongated while decreasing the area necessary forforming the groove 24. The groove 24 d having a circular shape in itscross section can be formed by wet etching, which, therefore, issuitable for a small light emitting device 50 with which the groove 24is hardly provided by machining.

The groove 24 and variation of the rear surface recess portion 221formed on the first lead 20 are described with reference to FIGS. 11 and12. A similar variation can also be applied to the groove 24 and therear surface recess portion 221 formed on the second lead 30.

As illustrated in FIG. 1B, the first lead 20 and the second lead 30 arepreferred to be exposed from the rear surface 14 to the side surfaces 15of the molded resin 11. With the above configuration, such an effect canbe produced that the light emitting device 50 is not angled with respectto the mounted substrate when the light emitting device 50 is mounted ona mounted substrate (not illustrated). A description is made below as tothe effect thereof.

Since the wettability of the molten solder with respect to the moldedresin 11 is low, so that, when the light emitting device 50 is mounted,the molten solder gathers to contact the first lead 20 and the secondlead 30 exposed from the molded resin 11. When the leads 20 and 30 areexposed only from the rear surface 14 of the molded resin 11, the moltensolder gathers only to the rear surface 53 of the light emitting device50. If an excessive amount of molten solder is applied, the excessivemolten solder may partially raise the light emitting device 50 to causethe light emitting device 50 to be mounted in an inclined manner.

To the contrary, if the leads 20 and 30 are exposed from the rearsurface 14 continuous to the side surface 15 of the molded resin 11, themolten solder expands to a side surface 54 from a rear surface 53 of thelight emitting device 50. Even with the excessive amount of the moltensolder, the excessive solder is discharged in a direction of the sidesurface 54 and thus only a proper amount of solder remains between therear surface 53 of the light emitting device 50 and the mountedsubstrate. Therefore, the light emitting device 50 can be prevented frombeing mounted in an inclined manner. Also, as illustrated in FIGS. 1Band 7, castellations (i.e., recesses) are provided on the rear surfaces22 and 32 of the leads 20 and 30 exposed from the side surfaces 15.Accordingly, an effect to hold the excessive solder can be enhanced andan area of the contact surface between the molten solder and the leads20 and 30 can be increased.

As illustrated in FIG. 7, when the leads 20 and 30 are exposed from therespective corresponding opposing side surfaces 15 of the molded resin11, the soldering flux may enter the boundary surface 61 between theleads 20 and 30 and the molded resin 11 from the boundary 61 b exposedfrom the side surface 15 of the molded resin 11. Therefore, it ispreferable to provide the groove 24 on the entry path of the solderingflux from the side surface 15 to prevent the soldering flux enteringfrom the boundary 61 b from reaching the recess portion 12. In otherwords, the groove 24 (i.e., 24X) is preferably formed along a portion13X of the side wall 13 provided between the side surface 15 and therecess portion 12 of the molded resin 11 (see, FIGS. 2 and 7).Accordingly, the entry of the soldering flux from the side surface 15can be controlled by the groove 24X.

When both of the grooves 24X and 24Y are formed, it is preferable thatthe groove 24X and the groove 24Y are connected to each other to beformed into a channel shape (see, FIG. 2). Accordingly, the clearancebetween the groove 24X and the groove 24Y can be eliminated. As a resultthereof, the entry of the soldering flux can be effectively controlled.

As illustrated in FIG. 9, the leads 20 and 30 are connected to the leadframe LF via tie bars TB. The tie bars TB have a width narrower thanthat of the leads 20 and 30 such that the tie bars TB can be cut laterwith ease. The leads 20 and 30 exposed from the side surfaces 15 of themolded resin 11 also work as the tie bars TB. Therefore, such aconfiguration that a length 24XL of the groove 24X is made longer than awidth TBW of the tie bars TB can improve an effect to control the entryof the soldering flux from the side surfaces 15.

As illustrated in FIG. 2, if the soldering flux enters from the sidewall 13Y opposing to each other near the side surfaces of the lightemitting component 40, a light absorption amount from the light emittingcomponent 40 increases. Therefore, as illustrated in FIGS. 6 and 8, itis preferable that the grooves 24Y are formed along the side wall 13Y togenerate stresses (i.e., the stress generated due to the thermalexpansion of the sealing resin 52 and the portion of the groove filledwith the resin 11 a) for pressing the areas of sides of the inside upperedges 241 of the portion of the groove filled with the resin 11 a duringthe reflow soldering. In other words, in the molded package 10, thegrooves 24Y are preferably formed on the surface 21 of the first lead 20along the portions 13Y in the adjacent to the portion (i.e., themounting area) on which the light emitting component 40 is mountedthereon later of the side wall 13. Accordingly the adhesion can beimproved between, especially, the portion of the groove filled with theresin 11 a and the corresponding bottom surface 243 of the grove 24Y ofthe boundary surface 61. Therefore, the soldering flux is stronglyprevented from entering the area in the adjacent to the light emittingcomponent 40 within the recess portion 12 through the boundary surface61 from the boundary line 61 a during the reflow soldering. As a resultthereof, the entry of the soldering flux from the side wall 13Y can becontrolled by the groove 24Y.

Preferably, the first lead 20 is provided with an additional groove 24Zon the surface 21 of the first lead 20 along a side 26 of the first leadpositioned opposite side of the second lead 30 (see, FIG. 6). Theadditional groove 24Z is entirely exposed from the bottom surface 121 ofthe recess portion 12 of the molded resin 11. With the additional groove24Z, such an effect is produced that the soldering flux entered from aside 26 can be prevented from reaching the light emitting component 40based on the following reason.

As illustrated in FIG. 2, the light emitting component 40 may bedisposed near the side 26. Since the soldering flux absorbs light, it ismaterial to control the soldering flux so as not to reach the area nearthe light emitting component 40 even when the soldering flux enters fromthe side 26. When the additional groove 24Z is not formed, the solderingflux entering the side 26 through the boundary surface 63 between thefirst lead 20 and the molded resin 11 from the rear surface 14 of themolded resin 11 can enter the mounting area for mounting the lightemitting component 40 along the boundary surface 64 between the surface21 of the first lead 20 and the sealing resin 52.

As illustrated in FIGS. 6 and 7, it is preferable to form the additionalgroove 24Z on the first lead 20 and fill a portion of the molded resin11 (i.e., the portion of the groove filled with the resin 11 a) into theadditional groove 24Z. The sealing resin 52 is well bonded to the moldedresin 11 within the additional groove 24Z, so that the soldering fluxcannot enter between the sealing resin 52 and the molded resin 11. Inother words, the entry path of the soldering flux is caused to detouralong the additional groove 24Z. In the portion of the groove filledwith the resin 11 a in the groove 24Z, the stress F₁ for pressingdownwardly (i.e., toward the bottom surface 243 of the groove 24Z) isgenerated due to the thermal expansion of the sealing resin 52 and theportion of the groove filled with the resin 11 a during the reflowsoldering. Accordingly, the adhesion becomes stronger at a position,especially, between the portion of the groove filled with the resin 11 aand the bottom surface 243 of the groove 24Z of the boundary surface 61,and thus the entry of the soldering flux can be highly controlled. As aresult thereof, the soldering flux can be prevented from being enteredfrom the boundary surface 63 by the groove 24Z.

In a small-sized light emitting device 50, since an area of the secondlead 30 is small, formation of the additional groove on the second lead30 is considered as being difficult; however, the additional groove mayalso be formed on the second lead 30.

A method for manufacturing the light emitting device 50 will bedescribed below.

<1. Manufacturing of Molded Package 10>

A lead frame LF having a plurality of pairs of the first lead 20 and thesecond lead 30 is formed by punching a metal plate, the first lead 20and the second lead 30 being opposed to each other in the lead frame LF.The first lead 20 and the second lead 30 are connected to the lead frameLF via the tie bars TB. Then, the grooves 24 are formed at predeterminedpositions of the first lead 20 and the second lead 30 according to thewet etching. The lead frame LF is held by a metal mold 90 havingclearances for the molded resin 11 at positions corresponding to therespective, lead pairs. Then, a resin material for the molded resin 11is injected into the clearance of the metal mold 90. After the resinmaterial is cured, the metal mold 90 is removed to obtain the moldedpackage 10 fixed to the lead frame LF.

<2. Mounting of Light Emitting Component 40>

Each of the light emitting components 40 (41, 42) illustrated in FIG. 2is provided with a pair of electrodes on the upper surface thereof. Inthe light emitting components 40, the light emitting components 40 aremounted on the first lead 20 of the molded package 10 via the diebonding.

As illustrated in FIG. 2, the first electrode (e.g., a p-side electrode)of the first light emitting component 41 is connected to the first lead20 via the bonding wire BW. The second electrode (e.g., an n-sideelectrode) of the first light emitting component 41 is connected to thefirst electrode (e.g., a p-side electrode) of the second light emittingcomponent 42 via the bonding wire BW. The second electrode (e.g., ann-side electrode) of the second light emitting component 42 is connectedto the second lead 30 via the bonding wire BW. Accordingly, the firstlight emitting component 41 and the second light emitting component 42are connected in series via the bonding wire BW.

The first electrodes (e.g., the p-side electrodes) of the first lightemitting component 41 and the second light emitting component 42 areconnected to the first lead 20 via the bonding wire BW and the secondelectrodes thereof (e.g., the n-side electrode) also can be connected tothe second lead 30 via the bonding wire BW. Accordingly, the first lightemitting component 41 and the second light emitting component 42 areconnected in parallel via the bonding wire BW.

The light emitting component provided with the first electrode on itsupper surface and the second electrode on its lower surface can also beemployed. In this case, the lower surface is fixed to the first lead 20by using conductive paste, thereby electrically connecting the secondelectrode with the first lead 20. The first electrode provided on theupper surface is electrically connected to the second lead 30 by usingthe bonding wire BW.

<3. Mounting of Zener Diode 43>

Each of the zener diodes 43 illustrated in FIG. 2 is provided with thefirst electrode (e.g., the p-side electrode) on its upper surface andthe second electrode (e.g., the n-side electrode) on its lower surface.The lower surface of the zener diode 43 is fixed to the second lead 30by using the conductive paste, thereby electrically connecting thesecond electrode with the second lead 30. The first electrode providedon the upper surface is electrically connected to the first lead 20 byusing the bonding wire BW.

<4. Filling of Sealing Resin 52>

The sealing resin in a liquid state is provided in the recess portion 12of the molded package 10 by potting, followed by curing thereof. Whenthe sealing resin is made into a double layer, a first sealing resin(e.g., an underfill resin) is provided in the recess portion 12 bypotting to cure the first sealing resin and, subsequently, the secondsealing resin (e.g., an overfill resin) is provided in the recessportion 12 by potting to cure the second sealing resin.

<5. Division of Light Emitting Devices 50>

The tie bars TB of the lead frame LF are cut along an outer surface ofthe molded resin 11 by dicing to divide the light emitting devices 50into pieces.

A material suitable for each composition member of the light emittingdevice 50 is described below.

(First Lead 20 and Second Lead 30)

The first lead 20 and the second lead 30 may be manufactured by using aconductive member including at least one or more of aluminum, iron,nickel, and copper in view of the processability and the strength of theresulting products. Preferably, the first lead 20 and the second lead 30are plated by using gold, silver, or an alloy thereof.

(Molded Resin 11)

Examples of the molding material of the molded resin 11 include athermosetting resin such as an epoxy resin, a silicone resin; and athermoplastic resin such as a liquid crystal polymer, a polyphthalamideresin and polybutylene telephthalate (PBT). Further, a white pigmentsuch as titanium oxide is mixed into the molding material to improve alight reflection ratio within the recess portion 12 of the molded resin11.

(Bonding Wire BW)

A metal-made wire made of a metal of, for example, gold, silver, copper,platinum, and aluminum, and alloys thereof can be used as the bondingwire BW.

(Sealing Resin 52)

A silicone resin, an epoxy resin, an acrylic resin, or a resincontaining at least one of the above resins can be used as a material ofthe sealing resin. The sealing resin 52 can be formed into a singlelayer or can be formed into a multi-layer (e.g., a double layer composedof the underfill and the overcoat).

Light scattering particles such as titanium oxide, silicone dioxide,titanium dioxide, zirconium dioxide, alumina, and aluminum nitride maybe dispersed within the sealing resin 52.

Particles of a material which converts a wavelength of light emittedfrom the light emitting element 40 (e.g., phosphor) may be dispersedwithin the sealing resin 52. For example, in the light emitting device50 for emitting white light, the light emitting element 40 for emittingblue light and phosphor particles for absorbing blue light to emityellow light (e.g., YAG particles) can be combined.

(Solder)

Examples of the solder to be used in the present embodiment can includeSn—Ag—Cu, Sn—Zi—Bi, Sn—Cu, Pb—Sn, Au—Sn, and Au—Ag.

<Modification>

FIG. 1 illustrates the light emitting device 50 of a type fixed to themounted substrate (not illustrated) at a side of the rear surface 53 ofthe light emitting device 50. However, also in the light emitting device50′ illustrated in FIG. 13, the grooves can also be provided on thesurfaces of the leads. The light emitting device 50′ differs from thelight emitting device 50 of FIG. 1 in that both of the first lead 20′and the second lead 30′ are exposed from the same side surface 54 so asto allow the side surface 54 to be fixed to the mounted substrate. Theother configurations of the light emitting device 50′ are identical tothose of the light emitting device 50 of FIG. 1.

Example

As one example, the molded package 10 and a comparative molded package100 are manufactured in order to confirm presence or absence of thegeneration of the burr 80.

The manufacturing method of the molded package 10 according to theexample will be described below. Firstly, the lead frame LF connected tothe first lead 20 and the second lead 30 via the tie bars TB issubjected to wet etching to form the grooves 24 at predeterminedpositions and thereafter the lead frame LF is held by the metal mold 90,thereby forming an assembly of the molded packages 10 by injecting aresin into the metal mold 90. Then, the molded resin 11 and the tie barsTB are cut along predetermined positions by dicing to divide the moldedpackages 10 into pieces.

The comparative molded package 100 is manufactured in the same manner asthe molded package 10 according to the example except for omitting theprocess of forming the grooves 24 at the predetermined positions bysubjecting to the wet etching.

As illustrated in FIG. 14A, in the comparative molded package 100, theburr 80 is generated between the leads 20 and 30 and the side wall 13 ofthe molded resin 11. On the other hand, as illustrated in FIGS. 14B and15, no burr was generated in the molded package 10 according to theexample.

In the molded package according to the present embodiment, the insideupper edge of the groove is exposed from the bottom surface of therecess portion of the molded resin and the outside upper edge of thegroove is embedded within the molded resin. The groove is filled withthe molded resin. Therefore, when viewed in cross section, the moldedresin filled in the groove (i.e., a portion of the groove filled withthe resin) is connected to a body of the molded resin at a side of theoutside upper edge and is exposed from the bottom surface of the recessportion at a side of the inside upper edge.

In a case of manufacturing the light emitting device by using the abovedescribed molded package, the recess portion of the molded package issealed with the sealing resin. After the sealing of the molded package,if the light emitting device is subjected to reflow soldering, thesealing resin expands within the recess portion to press the side wallof the recess portion and the bottom surface, respectively, outwardlyand downwardly. Further, since the molded resin also expands, theportion of the groove filled with the resin presses the side surfacesand the bottom surface within the groove. Still further, the portion ofthe groove filled with the resin is pressed by the expanded sealingresin since it is contacting the sealing resin. In other words, owing tothe synergistic effect between the expansion of the sealing resin andthe expansion of the portion of the groove filled with the resin, astress that the portion of the groove filled with the resin appliesdownwardly (i.e., toward the bottom surface of the groove) increases.

Upon invasion of the soldering flux, the soldering flux passes throughbetween the portion of the groove filled with the resin and the bottomsurface of the groove. However, while the soldering flux is in a moltenstate (i.e., is subjected to the reflow soldering), since the portion ofthe groove filled with the resin is pressed toward the bottom surface ofthe groove due to the expansion of the sealing resin and the portion ofthe groove filled with the resin, adhesion, especially, between theportion of the groove filled with the resin and the bottom surface ofthe groove in the boundary surface becomes stronger, which exerciseshigher resistant against the invasion of the soldering flux.

In the molded package of the present embodiment, the groove comes toposition immediately below the corners of the convex portion of theupper metal mold during the molding of the molded resin. Therefore, evenwith the corners of the convex portion being subjected to the chamferingprocessing, clearances having a sharp angle cannot be formed between thecorner and the corresponding lead. Therefore, the molten resin isprevented from being oozed out into the metal mold-lead contact area,resulting in preventing the burr from being formed.

As described above, according to the molded package of the presentembodiment, when the molded package is used in the light emittingdevice, the soldering flux can be effectively prevented from enteringthe recess portion of the molded package as well as the burr of themolded resin can be prevented from being generated within the recessportion.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

What is claimed is:
 1. A light emitting device comprising: a moldedpackage comprising: a recess; two leads; and a molded resin part, a partof the recess being defined by a side wall formed from the molded resinpart, at least one of the two leads comprising an upper-surface portionexposed from a bottom surface of the recess; and one or more lightemitting components, wherein the at least one of the two leads comprisesa groove at an upper surface thereof, the groove being filled with afirst part of the molded resin part, wherein the first part of themolded resin part comprises a first portion and a second portion, thefirst portion being exposed from the bottom surface of the recess, thesecond portion connecting with a bottom surface of the side wall, andwherein the groove has a depth smaller than a thickness of the at leastone of the two leads not to penetrate through the at least one of thetwo leads, and the groove being located outside of a mounting area formounting the light emitting component, wherein the groove has an insideupper edge and an outside upper edge, the inside upper edge beingpositioned at the upper-surface portion to exposed from the bottomsurface of the recess, the outside upper edge being positioned below theside wall to be embedded in the side wall, and wherein the groove isenclosed by connecting the inside upper edge and the outside upper edgeto each other.
 2. The light emitting device according to claim 1,wherein a cross section of the groove has a maximum width larger than adistance between the inside upper edge and the outside upper edge. 3.The light emitting device according to claim 1, wherein the groove isformed at a peripherally disposed portion of an inner surface of theside wall.
 4. The light emitting device according to claim 1, whereinthe groove is formed along three sides of the at least one of the twoleads.
 5. The light emitting device according to claim 1, wherein thegroove is formed along the one side of the at least one of the twoleads, a length of the groove being longer than a width of theprotrusion.
 6. The light emitting device according to claim 1, whereinthe groove has a C-shape or a U-shape when viewed from a top view. 7.The light emitting device according to claim 1, wherein theupper-surface portion of the at least one of the two leads includes themounting area for mounting the light emitting component thereon, thegroove surrounding at least a part of the mounting area when viewed froma top view.
 8. The light emitting device according to claim 1, whereinthe depth of the groove is smaller than a height of the light emittingcomponent.
 9. The light emitting device according to claim 1, whereinthe molded resin part includes a white pigment.
 10. The light emittingdevice according to claim 1, wherein the at least one of the two leadshas a side-surface exposed portion exposed from the outer side surfaceof the molded resin part, the side-surface exposed portion being flushwith the outer side surface of the molded resin part.
 11. The lightemitting device according to claim 1, wherein the upper-surface portionof the at least one of the two leads includes the mounting area formounting the light emitting component thereon, wherein the at least oneof the two leads has an rear-surface exposed portion exposed from a rearsurface of the molded resin part and positioned below the mounting area.12. The light emitting device according to claim 1, wherein the at leastone of the two leads has an rear-surface exposed portion exposed from arear surface of the molded resin part and comprises a concave extendingfrom an edge of the rear-surface exposed portion toward the uppersurface of the at least one of the two leads, the concave having acurved inner surface.
 13. The light emitting device according to claim1, wherein the at least one of the two leads has an rear-surface exposedportion exposed from a rear surface of the molded resin part andcomprises a concave extending from an edge of the rear-surface exposedportion toward the upper surface of the at least one of the two leads,the concave having a stepped inner surface.
 14. The light emittingdevice according to claim 1, wherein the height of the side wallmeasured from the upper surface of the at least one of the two leads islarger than a thickness of the at least one of the two leads.
 15. Thelight emitting device according to claim 1, wherein the at least one ofthe two leads is exposed from a rear surface to the outer side surfaceof the molded resin part.
 16. The light emitting device according toclaim 1, wherein the at least one of the two leads is provided with aprotrusion extending from one side thereof to an outer side surface ofthe molded resin part so that an end face of the protrusion is exposedfrom the outer side surface, the end face being flush with the outerside surface of the molded resin part, and wherein the protrusion ispositioned on a second part of the molded resin part to be in directcontact with the second part of the molded resin part at a rear side ofthe protrusion.